Dissolved, labile, and total particulate trace metal dynamics on the northeast greenland shelf

• Published in: Global Biogeochemical Cycles
• Main Authors: Chen, X.G., Krisch, S., Al Hashem, A., Hopwood, M.J., Rutgers van der Loeff, M.M., Huhn, O., Lodeiro, Pablo, Steffens, T., Achterberg, E.P.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2022
• Subjects: Isòtops; Oxigen dissolt en l'aigua; Aigües minerals; Isotopes; Oxigeno disuelto en agua; Mineral waters; Arctic; Arctic Ocean; Greenland; glacier; North Atlantic
• Online Access: http://hdl.handle.net/10459.1/84708; https://doi.org/10.1029/2022GB007528

We present high-resolution profiles of dissolved, labile, and total particulate trace metals (TMs) on the Northeast Greenland shelf from GEOTRACES cruise GN05 in August 2016. Combined with radium isotopes, stable oxygen isotopes, and noble gas measurements, elemental distributions suggest that TM dynamics were mainly regulated by the mixing between North Atlantic-derived Intermediate Water, enriched in labile particulate TMs (LpTMs), and Arctic surface waters, enriched in Siberian shelf-derived dissolved TMs (dTMs; Co, Cu, Fe, Mn, and Ni) carried by the Transpolar Drift. These two distinct sources were delineated by salinity-dependent variations of dTM and LpTM concentrations and the proportion of dTMs relative to the total dissolved and labile particulate ratios. Locally produced meltwater from the Nioghalvfjerdsbræ (79NG) glacier cavity, distinguished from other freshwater sources using helium excess, contributed a large pool of dTMs to the shelf inventory. Localized peaks in labile and total particulate Cd, Co, Fe, Mn, Ni, Cu, Al, V, and Ti in the cavity outflow, however, were not directly contributed by submarine melting. Instead, these particulate TMs were mainly supplied by the re-suspension of cavity sediment particles. Currently, Arctic Ocean outflows are the most important source of dFe, dCu, and dNi on the shelf, while LpTMs and up to 60% of dMn and dCo are mainly supplied by subglacial discharge from the 79NG cavity. Therefore, changes in the cavity-overturning dynamics of 79NG induced by glacial retreat, and alterations in the transport of Siberian shelf-derived materials with the Transport Drift may shift the shelf dTM-LpTM stoichiometry in the future.